Earlier quoted context omitted.
In which case, could you hibernate the CPU as well as the screen, but still leave the time on display?
but then you are defeating the purpose of wearing a smartwatch, which I believe is to keep receiving notifications for calls, emails, messages and so on. If you only wake up the CPU every minute to check then it's far too slow to be useful.
Is the idea of a smartwatch to be your main phone, small enough to strap to your wrist? I imagined that it was more like a really good watch - primarily there to tell the time, but allowing you to use it as a phone when that would otherwise be inconvenient.
I played around with a prototype of an Android watch, and it just seemed too small to be useful. It seems like a remote control to a smartphone would be more useful - something that vibrated when I get a notification, and could send commands to Siri.